This invention relates to an optical disk recording/reproducing device for recording/reproducing information with respect to an optical disk, and more particularly to an optical disk recording/reproducing device capable of effectively preventing the occurrence of recording/reproducing errors caused by the inclination or eccentricity of an optical disk.
With the evolution of a high-level information-oriented society, optical disk recording/reproducing devices capable of recording information on optical disks as information recording mediums with high precision and high density and/or reproducing the information recorded in the above-described manner, have been developed. Optical disks used in conjunction with the above device are compact disk (CDs), laser disk (LDs), and digital video disks or digital versatile disks (DVDs). Of these disks, DVDs can be formed with super-large capacities and have received much attention.
Unlike a fixed type magnetic disk device (i.e., hard disk device), in the optical disk recording/reproducing device, recording media, that is, optical disks can be replaced. The optical disk recording/reproducing device has a disk rotating mechanism constructed by, for example, a spindle motor for rotating the optical disk and uses a clamp mechanism to chuck the optical disk inserted into the optical disk recording/reproducing device on a turn table of the spindle motor.
In the above optical disk recording device, the precision with which the optical disk is chucked on the disk rotating mechanism, significantly influences the operation of the information recording/reproducing. That is, in a worst case scenario, if the optical disk is chucked in an inclined state or the optical disk is eccentrically chucked on the disk rotating mechanism, it becomes impossible to perform the information recording or reproducing operation.
If the optical disk is chucked in an inclined state, an error of the axis of the optical system becomes large. This error referred to as a tilt angle or as "tilt" indicates the angle made by a vertical axis perpendicular to the recording surface of the optical disk with respect to the optical axis of the optical pickup. When the tilt exceeds a permissible range, it becomes practically impossible to effect the information recording/reproducing operation.
Further, if the optical disk is eccentrically chucked, the spot of the light beam deviates from the track of the optical disk. This deviation is called a track error, and when it exceeds a permissible range as in the case of the tilt angle, it becomes practically impossible to effect the information recording/reproducing operation.
In optical disks recently developed or optical disks of large capacity (such as DVDs), since the information recording density is extremely high, it becomes necessary to, strictly manage the tilt angle or track error in comparison with the conventional case, in order to effect the precise recording/reproducing operation.
Therefore, in the optical disk device for effecting the recording/reproducing operation with high density, a mechanism for correcting the inclination of the optical disk by use of a servo motor or a mechanism for controlling the angle of the optical axis of the optical pickup to follow the tilt angle is provided.
However, provision of the servo mechanism makes the device structure complex and increases the cost of the device. Further, if the permissible error caused at the time of manufacturing of the optical disk and the disk rotating mechanism is set to an extremely restrictive range, the manufacturing cost increases.